The antimicrobial activity and phenolic compounds of five Finnish honey products against important human pathogens Streptococcus pneumoniae, S. pyogenes, Staphylococcus aureus, and methicillin-resistant S. aureus were analyzed. Microbroth dilution method and HPLC-DAD were used in antimicrobial testing and phenolic compound determination, respectively. Significant antimicrobial activity (p < 0.01) against all the tested pathogens was found from willow herb (Epilobium angustifolium), heather (Calluna vulgaris), and buckwheat (Fagopyrum esculentum) honeys. This is the first report on antimicrobial activity of Finnish monofloral honeys against streptococcal and staphylococcal bacteria. To our knowledge this is also the first report on the antimicrobial effect of honey against S. pneumoniae.

Milk oligosaccharides have been shown to interfere with adhesion of many pathogens to host mucosal surfaces. Characterization of the adhesion mechanisms of the bacteria to host cell surface is needed to develop novel functional food, infant formulas, and anti-infective drugs. Adhesion of Neisseria meningitidis, a human specific pathogen causing meningitis and septicemia, is not completely understood but is mediated by type IV pili. Here, we developed a microtiter well pili binding assay to investigate the binding activities of N. meningitidis isolated type IV pili to different glycoproteins. Pili binding activities to bovine thyroglobulin and human salivary agglutinin but not to chicken ovalbumin were present. Inhibition of these binding activities was demonstrated by fractionated human or bovine milk oligosaccharides. The binding of neisserial pili to bovine thyroglobulin was most effective and was clearly inhibited by human milk neutral or bovine milk acidic oligosaccharides.

In Kenya, leaves and roots from Croton macrostachyus are used as a traditional medicine for infectious diseases such as typhoid and measles, but reports on possible antimicrobial activity of stem bark do not exist. In this study, the antibacterial and antifungal effects of methanol, ethyl acetate and butanol extracts, and purified lupeol of C. macrostachyus stem bark were determined against important human gram-negative pathogens Escherichia coli, Salmonella typhi, Klebsiella pneumoniae, and Enterobacter aerogenes, gram-positive Listeria monocytogenes, and a fungus Candida albicans. The most promising broad scale antimicrobial activity against all the studied pathogens was shown by the ethyl acetate extract. The ethyl acetate extract induced the zone of inhibition between 10.1 ± 0.6 mm and 16.0 ± 1.2 mm against S. typhi, E. coli, K. pneumoniae, E. aerogenes, and L. monocytogenes with weaker antimicrobial activity against C. albicans (zone of inhibition: 5.6 ± 1.0 mm). The antibiotic controls (amoxicillin, ciprofloxacin, ampicillin, benzylpenicillin, clotrimazole, and cefotaxime) showed antimicrobial activity with zones of inhibition within 13.4 ± 0.7–22.1 ± 0.9 mm. The ethyl acetate extract had MIC in the range of 125–250 mg/mL against all the studied bacteria and against C. albicans MIC was 500 mg/mL. The present results give scientific evidence and support the traditional use of C. macrostachyus stem bark as a source for antimicrobials. We show that C. macrostachyus stem bark lupeol is a promising antimicrobial agent against several important human pathogens.